PDBsum entry: 2dx1

Signaling protein

PDB id: 2dx1

Contents

Protein chain

385 a.a. *

Waters ×64

* Residue conservation analysis

PDB id:

2dx1

Name:

Signaling protein

Title:

Crystal structure of rhogef protein asef

Structure:

Rho guanine nucleotide exchange factor 4. Chain: a. Fragment: residues 59-540. Synonym: apc-stimulated guanine nucleotide exchange factor, asef. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Expressed in: cell free protein synthesis.

Resolution:

2.36Å R-factor: 0.232 R-free: 0.299

Authors:

K.Murayama,M.Kato-Murayama,T.Terada,M.Shirouzu,S.Yokoyama, Riken Structural Genomics/proteomics Initiative (Rsgi)

Key ref:

K.Murayama et al. (2007). Crystal structure of the rac activator, Asef, reveals its autoinhibitory mechanism. J Biol Chem, 282, 4238-4242. PubMed id: 17190834 DOI: 10.1074/jbc.C600234200

Date:

22-Aug-06 Release date: 02-Jan-07

Protein chain

Q9NR80  (ARHG4_HUMAN) -  Rho guanine nucleotide exchange factor 4

Seq: 690 a.a.

Struc: 385 a.a.

 Gene Ontology (GO) functional annotation 

• Cellular component: intracellular (1 term)
• Biological process: regulation of Rho protein signal transduction (1 term)
• Biochemical function: guanyl-nucleotide exchange factor activity (2 terms)

DOI no: 10.1074/jbc.C600234200

J Biol Chem 282:4238-4242 (2007)

PubMed id: 17190834

Crystal structure of the rac activator, Asef, reveals its autoinhibitory mechanism.

K.Murayama, M.Shirouzu, Y.Kawasaki, M.Kato-Murayama, K.Hanawa-Suetsugu, A.Sakamoto, Y.Katsura, A.Suenaga, M.Toyama, T.Terada, M.Taiji, T.Akiyama, S.Yokoyama.

ABSTRACT

The Rac-specific guanine nucleotide exchange factor (GEF) Asef is activated by binding to the tumor suppressor adenomatous polyposis coli mutant, which is found in sporadic and familial colorectal tumors. This activated Asef is involved in the migration of colorectal tumor cells. The GEFs for Rho family GTPases contain the Dbl homology (DH) domain and the pleckstrin homology (PH) domain. When Asef is in the resting state, the GEF activity of the DH-PH module is intramolecularly inhibited by an unidentified mechanism. Asef has a Src homology 3 (SH3) domain in addition to the DH-PH module. In the present study, the three-dimensional structure of Asef was solved in its autoinhibited state. The crystal structure revealed that the SH3 domain binds intramolecularly to the DH domain, thus blocking the Rac-binding site. Furthermore, the RT-loop and the C-terminal region of the SH3 domain interact with the DH domain in a manner completely different from those for the canonical binding to a polyproline-peptide motif. These results demonstrate that the blocking of the Rac-binding site by the SH3 domain is essential for Asef autoinhibition. This may be a common mechanism in other proteins that possess an SH3 domain adjacent to a DH-PH module.

Selected figure(s)

Figure 1.
FIGURE 1. Structure of Asef. a, schematic presentation of the domain architecture of Asef. b, ribbon representation of the crystal structure of Asef. The SH3, DH, and PH domains are colored magenta, yellow, and blue, respectively. The regions that could not be assigned in the electron density map are depicted as dashed lines (loops) and by a gray box (ABR). The electron density in two loop regions of the PH domain was not clear due to disorder, and therefore, these regions were not modeled completely.

Figure 3.
FIGURE 3. Docking model of the Asef DH domain and Rac. In the model, Rac (green) is located on the structure of the MD-simulated (2 ns) Asef (yellow), with the straight 6 helix, by superimposing the DH domains of Asef and the Rac-Tiam1 complex. The PH domain was omitted from the figure for clarity. The bent 6 helix in the crystal structure of Asef is superimposed in red, and its movement is indicated by the curved black arrow. The switch-2 region, which clashes with the bent 6 helix, is indicated with a black arrow.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2007, 282, 4238-4242) copyright 2007.

Figures were selected by an automated process.